The U.S. risks a slow economy, fraud and a disenfranchised underclass, among other problems, if it renounces birthright citizenship. Countries that have done so have had to reconsider.

We can already see the future of our nation if it renounces birthright citizenship for the children of undocumented immigrants, and it isn't pretty. Dragging economies, new forms of fraud, a disenfranchised underclass, children deported to places they have never even visited — countries that do not have birthright citizenship have experienced these problems and more, and have been forced to reconsider their practices. Germany, Israel and Japan are just three of those countries, and their experiences have much to teach us.

The current debate about the future of the Constitution's 14th Amendment, which guarantees citizenship for all born on U.S. soil, centers on the question of individual fairness: Should these children have the right to U.S. citizenship although their birth on U.S. soil was the result of their parents' unauthorized presence here? The debate is really about what citizenship and belonging mean in the United States — profound and important issues but not ones that draw easy consensus. But if we ask what will happen to our society as a whole if we eliminate birthright citizenship, the facts become easy to see.

Since the birth of modern Germany, that country has followed the jus sanguinis, or "right of blood," principle of citizenship, in which any German descendant could claim German citizenship while the children of foreigners — even legal immigrants — born in Germany could not. To meet labor needs while keeping Germany as German as possible, the government implemented guest-worker programs to bring in foreigners for temporary stays.

But things did not work out as planned. Some guest workers remained, and as the economy grew and the workforce aged, immigrants kept coming — both inside and outside the law. Their German-born noncitizen children began to form a vast underclass. These children had known only Germany and German in their young lives but were stuck in a no man's land as people without a country.

So in 2000, Germany made its citizenship laws just a little more like ours. Children born on German soil could claim German citizenship, but only if at least one of their parents had lived in the country legally for eight years. The children born in Germany of two undocumented parents still are not German citizens at birth. The result is an underground market in fraudulent paternity, in which German men who are citizens — derogatorily known as imbissvaeter, or fast-food fathers — claim to be a child's father in exchange for a fee, thus enabling the child to be a German citizen.

Far from promoting the rule of law, Germany's approach to citizenship has created a mess. Unless the U.S. implemented mandatory DNA testing, which many would consider an invasion of privacy, it is likely that a similar black market in paternity would emerge here if birthright citizenship were eliminated.

Over its 60 years of existence, Israel also has had a jus sanguinis system, in which Jews the world over and the descendants of Israeli Arabs can claim citizenship but the children of foreign workers born on Israeli soil cannot. Like Germany, Israel sought to meet labor needs by importing temporary workers — largely from Asia and Eastern Europe — who did not end up being so temporary. The result: The Israeli government announced in August plans to deport 400 Israeli-born children of non-Jewish immigrants. These are children who speak Hebrew, have always expected to perform the obligatory military service that Israel requires of its citizens and know Israel as their only home.

The controversy is dividing Israel. The national organization of Holocaust survivors has called for a halt to the deportations, expressing its sense of shame that "a Jewish government could operate without a conscience and in such an inhumane way." Israelis have taken to the streets to demand that their system move just a step toward the U.S. system and at least grant these children legal residency status.

Some say birthright citizenship motivates immigration, and thus a country without it will attract fewer immigrants. Well, not in Japan. Though Japan historically has had fewer immigrants than most developed countries, in 2008 more immigrants than ever before — including 100,000 undocumented immigrants — lived within its borders. It is an island nation and has never had a large guest-worker program and does not confer birthright citizenship. But in recent decades, these policies became a drag on the economy, creating labor shortages and making it difficult to attract high-skilled immigrants.

Change has been slow, but Japan is reexamining its approach to immigration and has given residency status to tens of thousands of "foreigners" born on Japanese soil.

In recent decades, other countries such as Australia and Britain that once conferred automatic birthright citizenship have added limitations for the children of undocumented immigrants. They too found that restrictions on birthright citizenship did not slow undocumented immigration.

Americans will have different opinions on what is fair to taxpayers or innocent children, to would-be immigrants waiting "in line" abroad or undocumented parents already here, to low-skilled American workers or striving newcomers seeking the American dream. What we have seen, however, is that when a country does not offer citizenship to all born on its soil, society as a whole suffers the consequences.

Julie M. Weise is an assistant professor in the international studies program at Cal State Long Beach.